Sayed Ibrahim Faculty at Technical University of Liberec, Department of Textile Technology Ph.D from Technical University of Liberec, Czech Republic Research.

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Presentation on theme: "Sayed Ibrahim Faculty at Technical University of Liberec, Department of Textile Technology Ph.D from Technical University of Liberec, Czech Republic Research."— Presentation transcript:

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Sayed Ibrahim Faculty at Technical University of Liberec, Department of Textile Technology Ph.D from Technical University of Liberec, Czech Republic Research Interest: Textile Technology and Quality Control Topic Characterization of Basalt Filaments in Longitudinal Compression

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Basics of textile engineering Fibers are the fundamental and the smallest elements constituting textile materials. The mechanical functional performance of garments are very much dependent on the fiber mechanical and surface properties, which are largely determined by the constituting molecules, internal structural features and surface morphological characteristics of individual fibers. Scientific understanding and knowledge of the fiber properties and modeling the mechanical behavior of fibers are essential for engineering of clothing and textile products. Molecular properties Fiber Properties Yarn Properties Fabric properties Fiber Structure Yarn Structure Fabric Structure Garment Structure Demands of using textiles in industrial application are very high and risk should be minimum i.e. precise characterization

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Basaltic rocks Basalt is generic name for solidified lava which poured out the volcanoes Basalt is 1/3 of earth Crust Basaltic rocks are melted approximately in the range 1500 – 1700  C. When this melt is quickly quenched, it solidificated to glass like nearly amorphous solid. Slow cooling leads to more or less complete crystallization, to an assembly of minerals. Augite Plagioclase Olivine

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Properties of Basalts Basalts are more stable in strong alkalis that glasses. Stability in strong acids is low Basalt products can be used from very low temperatures (about –200  C) up to the comparative high temperatures 700 – 800  C. At higher temperatures the structural changes occur.

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Samples Preparation The marbles and filament roving are prepared. From marbles the thick rods were prepared by grinding. The roving contained 280 single filaments are used. Mean fineness of roving was 45 tex.

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Statistical analysis Main aim of the statistical analysis is specification of R(  ) and parameter estimation based on the experimental strengths (  i ) i=1.....N. Based on the preliminary computation it has been determined that for basalt fibers strength the Weibull distribution is suitable

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Testing The individual basalt fibers removed from roving were tested. The loads at break were measured under standard conditions at sample length 10 mm. Load data were transformed to the stresses at break  i [GPa] Sample of 50 stresses at break

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Maximum likelihood estimation When  i i=1,...N are independent random variables with the same probability density function f(  ) = F’(  i, a) the logarithm of likelihood function has the form ln L =  ln f((  i, a) The a are parameters of corresponding risk function. The MLE estimators a* can be obtained by the maximization of ln L(a).

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Parameter estimates ModelA [GPa]B [GPa]C [-]ln L(a*) WEI30.06410.2301.37033,50 WEI2-0.3011.82929.164  The differences between three and two parameters Weibull distribution are identified by the values of maximum likelihood function ln L(a*).  The three-parameter Weibull distribution was selected as suitable for glass and tempered basalt samples as well

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Thermal exposition II Basalt filament roving tempered at T T = 20, 50, 100, 200, 300, 400 and 500 o C in times t T = 15 and 60 min. The dependence of the roving strength on the temperature exhibits two nearly linear regions. One at low temperature to the 180 o C with nearly constant strength and one up to the 340 o C with very fast strength drop

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Thermal exposition III 1. Tempered basalt fibers from roving were tested. 2. The apparatus based on the torsion pendulum principle was used. (fiber of length l o hanged with pendulum period P and amplitude A, successive oscillations were measured, the shear modulus of circular fiber is calculated) 3. The shear modulus G =11-21 GPa is comparatively high. The prolongation of tempering leads to high drop of G. lolo

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Thermo mechanical analysis (TMA) In TMA the dimensional changes are measured under defined load and chosen time Special device TMA CX 03RA/T has been used Sample is placed on the movable holder (in oven) connected with displacement sensor, which measures dimensional changes

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Non-isothermal compressive creep The responses of basalt to the compressive loads under non-isothermal conditions were investigated from creep type experiments. The load was 200 mN. For the basalt rod the dependence of sample height L on the temperature T (increased linearly with time t )were measured. Starting temperature was T o = 30 o C and rate of heating was 10 o C/min. For avoiding the initial The dilatation d i = L o – L has been recorded

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Creep model I From isothermal experiments is deduced that the rate of creep only is markedly temperature dependent. The rate of height changes can be expressed by differential equation K is the rate constant is sample height in equilibrium. Function f(.) is creep rate model.

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Creep model II The classical reaction kinetics the creep rate can be expressed in the form where n is constant (order of reaction). For n=1 the simple exponential model of creep (rate process of first order) results. Temperature dependence of the creep rate constant K

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Creep model III In non-isothermal conditions it is assumed that temperature dependent is rate constant only By the formal integration of this eqn. for exponential type model (n = 1) the following relation results

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Creep model IV For the case of linear heating during creep is valid Symbol T o denotes initial temperature and G(x) is the integral where  is rate of heating

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Approximation of integral Simple and precise approximation of temperature term has the form The relative error of approximation is for E/RT<7 under 1%.

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Parameter estimation These should be estimated from experimental data. The nonlinear regression have to be used. More simple is to use rate equation for first order model combined with Arrhenius dependence in the linearized form Application of this equation requires knowledge of L  and computation of creep rate

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Creep rate The rate of creep curve can be derived from Reinsch smoothing procedure (s=1)

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Creep discussion More precisely it will be necessary to use general order of rate process and investigate n as well Thermally stimulated creep is successfully used in the area of polymers. In non-polymeric solids where compressive creep is due to rearrangements of molecular clusters and structural reordering are rate models quite useful.

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Modulus estimation The  K was estimated by the image analysis value  K = 0,9 was obtained. The modulus E C at individual temperatures F = 200 mN is load, A K = 20.725 mm 2 is cross sectional area  K(10) is deformation under compressive creep in time t = 10 s. By the same way the modulus E E was estimated from the compressive creep curve of pure epoxy resin

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Textile structures The basalt filament yarns were prepared with fineness 40x2x3. Knits and sewing thread were created. Utilization of basalt for preparation of knitted fabric was without problems During sewing tests the basalt yarns were frequently broken due to its brittleness. The composite basalt thread coated by PET was prepared.

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Emitted particles analysis Some characteristics of the basalt fibers are similar to the asbestos. Since the mechanisms for asbestos carcinogenicity are not fully known it cannot be excluded that basalt fibers may also be hazardous to health. Thus there is a need for analysis of fibrous fragment characteristics in production and handling in order to control their emission.

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Fragmentation The weave from basalt filaments was used. The fragmentation was realized by the abrasion on the propeller type abrader. Time of abrasion was 60 second. It was proved by microscopic analysis that basalt fibers are not split and the fragments have the cylindrical shape.

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Analysis Fiber fragments were analyzed by the image analysis, system LUCIA M. The fragments shorter that 1000  m were analyzed. Results were lengths L i of fiber fragments. For comparison the diameters D i of fiber fragments were measured as well.

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Fragmentation conclusion It is known, that from point of view of cancer hazard the length/diameter ratio R is very important. For basalt fiber fragments is ratio R = 230.51/11.08 = 20.8. Despite of fact that basalt particle are too thick to be respirable the handling of basalt fibers must be carried out with care.